The present invention relates to systems control modules having switches, control knobs and/or indicators, particularly flight deck panels for aircraft which may include light plates and control devices such as toggle switches, rotary switches, lighted and nonlighted push button switches, rheostats, and indicator lights.
The flight deck (cockpit) area of a modem commercial aircraft includes an extremely large number of different types of switches and status indicating lights (annunciators) for different aircraft system control functions. Due to the large number of control and indicating devices, they are arranged in modules, encompassing large areas viewable and reachable by the flight crew. Modules having similar control or indicating functions may be arranged and located similarly in the flight decks of different aircraft, for ease of use by the flight crew. Also, similar switches, both with respect to look and feel, are provided for similar functions. For example, a small flight deck module may incorporate a row of toggle switches for on-off operation of aircraft lights (beacon, navigation, strobe, wing, and so on) arranged at approximately the same location in different aircraft with differently shaped operating levers for tactile recognition by a pilot. Other systems may be controlled by rotary switches push button switches, or rheostats. A particular panel may or may not incorporate annunciators, and some panels may consist solely of banks of annunciators to indicate the status of different flight control systems.
The electrical systems controlled by the various switches and indicated by the various annunciators operate from standardized electrical power. In addition, flight crews have become accustomed to the look and feel of past flight deck panels and modules, which typically include incandescent lights for annunciators which operate similarly in terms of brightness for corresponding annunciators of different aircraft. The flight control modules have been designed to allow replacement of failed incandescent annunciator lights. This requires mechanical components that can be opened or disassembled for access to the lights. Special materials and heat tolerant and heat dissipating components also are required adjacent to the lights. As noted above, provision must be made for different types of switches, and also for switches of different manufacturers. Switch contacts become worn over time, necessitating switch replacement and rewiring. Many modules will have several switches and several different types of switches, each of which must be hard wired to a control circuit, in addition to the front light plate with a standard connector to supply power for lighting the panel. Nevertheless, it is desirable that a reasonably small number of system connectors be provided for each panel, for ease of installation, replacement, and repair. Thus, wires from several individual switches and annunciators typically are bundled and soldered to system connectors.
The present invention provides a novel systems control panel and novel components, namely, different types of switches and annunciators, having common dimensions, interchangeability with respect to existing panels, and the same tactile and visual human interface with the panels. The new panels also are of much greater reliability and less weight, incorporate component parts appropriate for automated manufacture and are easier to install and maintain. In fact, it is envisioned that virtually no maintenance will be required for the life of the aircraft, including no need for switch or annunciator light replacement.
In one aspect of the present invention, a systems control panel includes a standard light plate having the same characteristics as the light plate of the panel being replaced. The light plate is mounted on a machined front plate. A front printed wiring board or assembly (PWA) is mounted a predetermined uniform distance behind the machined front plate, and can incorporate a connector to mate with the electrical connector of the light plate. Actuation and annunciator components are mounted in the machined front plate and carry magnets that cooperate with Hall effect devices on the front PWA. For example, in the described embodiment the switches carry small magnets which, by manipulation of operating switch levers or knobs, move into and out of close proximity to magnet sensitive switching devices mounted on the front PWA. No mechanical contacts are required, and the switch actuating components are not mounted internally of discrete switches. Rather than hard wiring each switch, all circuits are routed within the PWA. To allow room for components mounted to the rear of the front PWA, a second or rear printed wiring assembly (PWA) can be provided, spaced a greater distance rearward from the front PWA and connected thereto by compliant pin connectors. On the back of the rear wiring board, standard system connectors are provided, compatible with system connectors of prior art system control panels, typically compliant pin connectors. When the design has been completed, the improved panel can be substituted for the preexisting panel with no additional alterations being required.
In another aspect of the present invention, the machined front plate and PWAs form a heat conductive assembly. The PWAs can have the usual power and ground planes and, additionally, one or more thermal planes, thermal vias, and heat conductive surface areas for engagement with a heat conductive housing. Heat from heat producing components secured on the PWAs is transferred by way of the thermal plane or planes, vias and surface conductors to the front plate and the housing for efficient dissipation of heat. The front PWA, including thermal planes and vias, is designed for a significant amount of thermal isolation of one side of the PWA from the other, while promoting heat conduction to the edges in contact with the heat conductive and heat dissipating housing.
Toggle switches which have actuating levers that swing in one plane can have rear end portions carrying magnets moved into and out of close proximity to Hall effect sensors stationarily mounted on the front PWA. Rotary switches can have magnets rotated into an out of close proximity to Hall effect devices mounted on the front PWA. Push button switches can have magnet carriers moved linearly toward and away from Hall effect devices mounted on the front PWA. Rheostat devices can have magnet carriers moved progressively toward or away from Hall effect devices mounted on the front PWA. For each device, appropriate circuitry is provided so that its operation emulates mechanical switches previously in use.
In another aspect of the invention, annunciator lights are LEDs which have a longer life and more reliable operation than incandescent lights. A plurality of LEDs can be provided for each annunciator, increasing reliability to the extent that routine replacement is not required. Thus, simpler mechanical constructions can be provided, and cheaper, lower temperature resistant materials used. In addition, since no hard wiring of individual switches is required, a considerable amount of bulk and weight is eliminated. For many control panels, the novel panels in accordance with the present invention will be several times smaller in terms of volume than corresponding panels currently in use.
In another aspect of the present invention, annunciator LEDs are enclosed in an annunciator housing, such LEDs being mounted directly on the front PWA, increasing the standardization of design and manufacture. Specialized reflectors and lenses are provided to increase viewability of annunciator indicia, particularly at sizable side angles.
In yet other aspects of the invention, improved switches are provided including toggle switches having cams for controlling detent positions, multiple rotary switches, and multiple rheostats incorporated within a single casing. Nevertheless, all switches are designed for mounting in the machined front plate to cooperate with Hall effect sensors mounted on the front PWA, for standardization of design.
In other aspects of the present invention, circuitry is provided for each systems control panel component for emulating operation of prior panels, such as by controlling operation of annunciator lights to resemble operation of incandescent lights, and providing circuitry compatible with standard system connectors.